Bethesda Softworks, the company that developed games such as Morrowind and Oblivion, has made its own map for Valve's hugely innovative Portal after being so infatuated with the title. Bethesda's level designer Daryl Brigner was responsible for creating the map, which is currently up to version 1.2 after a few tweaks have been made.

The map is available for the PC version of Portal only and can be downloaded at TWHL.